Metabolic stress at cycling critical power vs. running critical speed

Introduction. - This aim of the present study was to compare metabolic rates at critical running speed vs. critical power in cycling. Summary of facts. - Eight participants (33.6 +/- 12.1 years) performed a series of constant-intensity exhaustive trials to model the speed-time(-1) (treadmill; 1% gradient) and power time(-1) relationship (cycle ergometry) for intercept of the two relationships to be determined (Critical Speed [CS], Critical Power [CP]). A time to exhaustion (tlim) at CS and CP then followed. tlim did not differ between conditions (CS: 30.2 +/- 4.7 min, CP: 26.8 +/- 1.4 min, p = 0.58). The mean VO2 values at minute 3 of the tlim were not significantly different with a strong relationship between the two sets of data (r = 0.87, p < 0.01). Values reached 86 +/- 2% (CS) and 90 +/- 2% of VO(2)max (CP) at end exercise, with no difference between the two sets of data (p < 0.05). Conclusion. - There is a metabolic, critical intensity (i.e. CS and CP) that induces similar metabolic stress, thus independent of the muscular contraction regimens. (C) 2013 Elsevier Masson SAS. All rights reserved.